#include <bits/stdc++.h>
using namespace std;
const int N=1e6+50;
struct Point{
    int x,y;
}p[N];
int n;
int cross(Point a,Point b,Point c,Point d){
    //printf("%d %d %d %d %d %d %d %d\n",a.x,a.y,b.x,b.y,c.x,c.y,d.x,d.y);
    //printf("%d\n",(b.x-a.x)*(d.y-c.y)+(b.y-a.y)*(d.x-c.x));
    return (b.x-a.x)*(d.y-c.y)-(b.y-a.y)*(d.x-c.x);
}
int main(void){
    while(~scanf("%d",&n) && n){
        for(int i=0;i<n;i++){
            scanf("%d%d",&p[i].x,&p[i].y);
        }
        p[n]=p[0];
        p[n+1]=p[1];
        bool flag=true;
        for(int i=0;i<n;i++){
            if(cross(p[i],p[i+1],p[i+1],p[i+2])<0){
                //printf("%d\n",cross(p[i],p[i+1],p[i+1],p[i+2]));
                flag=false;
                break;
            }
        }
        if(flag){
            printf("convex\n");
        }else{
            printf("concave\n");
        }
    }
    return 0;
}